Global patterns of marine turtle bycatch

Wallace, Bryan P.; Lewison, Rebecca L.; McDonald, Sara; McDonald, Richard K.; Kot, Connie Y.; Kelez, Shaleyla; Bjorkland, Rhema; Finkbeiner, Elena M.; Helmbrecht, S’rai; Crowder, Larry B.

doi:10.1111/j.1755-263x.2010.00105.x

Cited by 278 publications

(233 citation statements)

References 28 publications

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“…Using onboard observer data, Gardner et al (2008) found seasonal changes in catch distributions of loggerhead and leatherback turtles in the North Atlantic, with patterns of spatial clustering from July to October. Analysed on a global scale, Wallace et al (2010b) were able to highlight region− gear combinations requiring urgent action such as gillnets, longlines and trawls in the Mediterranean Sea and eastern Pacific Ocean. Generating such estimates of catch rates and spatial/temporal patterns for entanglement are not yet possible due to the lack of quantitative information.…”

Section: Differentiation From Bycatchmentioning

confidence: 99%

A global review of marine turtle entanglement in anthropogenic debris: a baseline for further action

Duncan¹,

Botterell²,

Broderick³

et al. 2017

Endang. Species. Res.

129

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Section: Differentiation From Bycatchmentioning

confidence: 99%

A global review of marine turtle entanglement in anthropogenic debris: a baseline for further action

Duncan¹,

Botterell²,

Broderick³

et al. 2017

Endang. Species. Res.

129

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“…Fisheries bycatch is recognized as perhaps the most serious global threat to highly migratory, long-lived marine taxa including turtles (Wallace et al 2010a, birds (Croxall et al 2012, Lewison et al 2012, mammals (Read et al 2006), and sharks (Dulvy et al 2008). Marine megafauna species are susceptible to fisheries bycatch because they occupy broad geographic distributions across geopolitical boundaries and oceanographic regions that support both small-and large-scale fisheries, and because their life histories (e.g., delayed maturity, low reproductive rates) make them particularly sensitive to sources of mortality that affect late life stages (Crouse et al 1987, Heppell et al 2005.…”

Section: Introductionmentioning

confidence: 99%

Impacts of fisheries bycatch on marine turtle populations worldwide: toward conservation and research priorities

et al. 2013

Self Cite

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Abstract. Fisheries bycatch is considered the most serious threat globally to long-lived marine megafauna (e.g., mammals, birds, turtles, elasmobranchs). However, bycatch assessments to date have not evaluated population-level bycatch impacts across fishing gears. Here, we provide the first global, multigear evaluation of population-level fisheries bycatch impacts for marine turtles. To compare bycatch impacts of multiple gears within and among marine turtle populations (or regional management units, RMUs), we compiled more than 1,800 records from over 230 sources of reported marine turtle bycatch in longline, net, and trawl fisheries worldwide that were published between 1990-2011. The highest bycatch rates and levels of observed effort for each gear category occurred in the East Pacific, Northwest and Southwest Atlantic, and Mediterranean regions, which were also the regions of highest data availability. Overall, available data were dominated by longline records (nearly 60% of all records), and were nonuniformly distributed, with significant data gaps around Africa, in the Indian Ocean, and Southeast Asia. We found that bycatch impact scores-which integrate information on bycatch rates, fishing effort, mortality rates, and body sizes (i.e., proxies for reproductive values) of turtles taken as bycatch-as well as mortality rates in particular, were significantly lower in longline fishing gear than in net and trawl fishing gears. Based on bycatch impact scores and RMU-specific population metrics, we identified the RMUs most and least threatened by bycatch globally, and found wide variation among species, regions, and gears within these classifications. The lack of regional or species-specific patterns in bycatch impacts across fishing gears suggests that gear types and RMUs in which bycatch has the highest impact depend on spatially-explicit overlaps of fisheries (e.g., gear characteristics, fishing practices, target species), marine turtle populations (e.g., conservation status, aggregation areas), and underlying habitat features (e.g., oceanographic conditions). Our study provides a blueprint both for prioritizing limited conservation resources toward managing fishing gears and practices with the highest population impacts on sea turtles and for enhancing data collection and reporting efforts.

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“…Third, exploitation of productive species, such as tunas, at MSY is driving steep population declines and elevating the risk of extinction of some unmanaged and less productive bycatch species. Tuna fisheries are directly responsible for endangering a wide range of oceanic pelagic sharks, billfishes, seabirds, and turtles (26,27).…”

Section: Discussionmentioning

confidence: 99%

Global population trajectories of tunas and their relatives

Juan‐Jordá

Mosqueira

Cooper

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

124

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Tunas and their relatives dominate the world's largest ecosystems and sustain some of the most valuable fisheries. The impacts of fishing on these species have been debated intensively over the past decade, giving rise to divergent views on the scale and extent of the impacts of fisheries on pelagic ecosystems. We use all available age-structured stock assessments to evaluate the adult biomass trajectories and exploitation status of 26 populations of tunas and their relatives (17 tunas, 5 mackerels, and 4 Spanish mackerels) from 1954 to 2006. Overall, populations have declined, on average, by 60% over the past half century, but the decline in the total adult biomass is lower (52%), driven by a few abundant populations. The trajectories of individual populations depend on the interaction between life histories, ecology, and fishing pressure. The steepest declines are exhibited by two distinct groups: the largest, longest lived, highest value temperate tunas and the smaller, short-lived mackerels, both with most of their populations being overexploited. The remaining populations, mostly tropical tunas, have been fished down to approximately maximum sustainable yield levels, preventing further expansion of catches in these fisheries. Fishing mortality has increased steadily to the point where around 12.5% of the tunas and their relatives are caught each year globally. Overcapacity of these fisheries is jeopardizing their longterm sustainability. To guarantee higher catches, stabilize profits, and reduce collateral impacts on marine ecosystems requires the rebuilding of overexploited populations and stricter management measures to reduce overcapacity and regulate threatening trade.

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Global patterns of marine turtle bycatch

Cited by 278 publications

References 28 publications

A global review of marine turtle entanglement in anthropogenic debris: a baseline for further action

A global review of marine turtle entanglement in anthropogenic debris: a baseline for further action

Impacts of fisheries bycatch on marine turtle populations worldwide: toward conservation and research priorities

Global population trajectories of tunas and their relatives

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